It is known that cortisone acetate exists in several polymorphic forms. Collard, R. E. (1961), Pharm. J., 186, 113-117 published photographs of 4.mu. particles of cortisone acetate which changed to particles of up to 100.mu. by suspension in water for less than 24 hours. Carless, et al., "Dissolution and crystal growth in aqueous suspensions of cortisone acetate", J. Pharm. Pharmac., 1968, 20, 630-638, describe a technique for limiting crystal growth of cortisone acetate by mixing 100 mg micronized cortisone acetate with 0.5 ml of 5% v/v solution of Nonidet P42 (Shell Oil Co. non-ionic wetting agent which has approximately 27% of a polyethylene oxide condensate as active material) in 0.9% w/v solution of sodium chloride. This was then gradually diluted with 9.5 ml of the Nonidet-sodium chloride solution. The cortisone acetate changes to the water stable form with very little change in size distribution, Carless, et al. "Effect of crystal form, cortisone alcohol and agitation on crystal growth of cortisone acetate in aqueous suspensions", J. Pharm. Pharmac., 1968, 20, 639-645.
U.S. Pat. No. 3,937,720 to Varma, et al. discloses steroids of the general structure ##STR2## and the 1,2-dehydro derivatives thereof, wherein R.sub.1 is chlorine, fluorine, or hydroxy and R'.sub.1 is hydrogen or R.sub.1 and R'.sub.1 together are .dbd.O; R.sub.2 is hydrogen or halogen; R.sub.3 is hydrogen, methyl, or fluorine; R.sub.4 is hydrogen, hydroxy, ##STR3## or halogen; R.sub.5 and R.sub.6 are the same or different and are hydrogen, alkyl, alkylthio, alkoxy, carboalkoxy, formyl, ##STR4## hydroxy, halogen, phenyl or cyano, with the proviso that when R.sub.5 and R.sub.6 are different, one of R.sub.5 and R.sub.6 is hydrogen, included within the above are 21-(acetyloxy)-9-fluoro 1',2',3',4'-tetrahydro-11.beta.-hydroxypregna-1,4-dieno-[16.alpha.,17-b]na phthalene-3,20-dione and (11.beta.,16.beta.)-9-fluoro-1',2',3',4'-tetrahydro-11,21-dihydroxypregna- 1,4-dieno[16,17-b]naphthalene-3,20-dione. It has been found that steroids as defined herein when micronized and suspended in water undergo a transformation to their monohydrate form within several hours with a concomitant increase in particle size. In fact, the micronized particles upon hydration grow from an average particle size of less than 20 microns and usually less than 10 microns into long needle-like crystals about 50 to 75 microns in length. These long crystals are undesirable because their smaller surface area may reduce dissolution rate and bioavailability.